The present invention relates to the working of lenses, and more particularly to the working of marginal zones of a lens.
In particular, the present invention relates to a method of working the marginal zones of a lens, particularly a contact lens, which is of soft and readily damaged material, and to an apparatus for carrying out the method.
There are lenses which are of relatively soft material that is therefore easily damaged, for instance by scratching or the like. The fact that these lenses are of soft material does not eliminate the need to properly work them, such as grinding them, polishing them and the like. However, the composition of the lens from such a material evidently imposes special problems in terms of handling the lens during the finishing or working operation to which it must be subjected. This is for instance true of contact lenses, which come either of relatively hard material or of relatively soft material, the latter being the type of material with which particular difficulties are being experienced.
It is known from German Pat. No. 2,102,820 to hold lenses of relatively soft material between two rotating spindles while their marginal zones are being ground or otherwise worked, and to direct a stream of a liquid cooling agent over the lens as well as the ends of the spindles which are adjacent to the same, in order to obtain a certain amount of rigidity of the marginal zones of the lens so that they can be worked without yielding excessively.
However, the actual application proposed in the aforementioned German patent is quite difficult and, therefore, time consuming and expensive. Moreover, the possibility is not reliably precluded that the lens might become damaged by scratching, due to relative movements of the lens and the supporting elements. In addition, the cooling of the lens-- which is necessary in this prior-art proposal-- brings with it the potential danger that the lens might break precisely because it is being so cooled.